gasses that have been run through a wash cansometimes absorb a considerable amount of water and their fluid data can then be significantly different from those of dry gasses.The process for calculating the density of water-ladengasses and making the necessary corrections to the flowmetering is detailed in the VDI / VDE 2040, Part 4. In this instance,

q

, Dm represents the mass flowaccording to the calculation sheet of your deltaflow.The radical term corresponds to the output signal of a root extracting differential pressure transducer.If the final value of the transducer is set to correspondwith the calculation sheet of your deltaflow, then the root extracted output signal of the dp-transducer is proportional to the flow measurement.

Calculating the Density of Natural Gas

Natural gas is actually a mixture of various gasses in varying combinations. The primary elements are usually methane and nitrogen as well as other hydrocarbons and pollutants.There are various calculation models available fordetermining gas density. The ideal gas equation is often used for basic control purposes.Custody transfer applications and measurements whichrequire a high degree of precision are usually calculated using the AGA or the GERG Equation.The AGA NX family of equations the standard in mostnon-European countries. This equation is described in the VDI / VDE 2040, Part 4.The GERG88 Equation was developed by European gassuppliers and is widely-used within the European region as a standard for calculating gas quantities. The GERG88 is described in the DVGW Worksheet G486. (DVGW is he

Flowmetering of Gasses and Steam

Prerequisite conditions for simplification: Constant expansion number, ideal gas behavior, constant conduit interior diameter.
,

dpdpTpTpqq

DBBDDBDmm Again in this equation, the last radical termcorresponds to the output signal of a root-extracting differential pressure transducer. The flow measurement, therefore, results from the designed mass flow multiplied by the output signal of a root- extracting transmitter. The density correction is handled by the middle radical term, which incorporates the operational pressure and temperature as well as the design pressure and temperature.You will find the design data (Index D) on thecalculation sheet for your deltaflow.The simplified flow equation for gasses can also beused to make a rough calculation of the volume measurement of overheated steam. German Technical and ScientificAssociation for Gas and Water and is headquartered inBonn, Germany.)

Simplified Calculation Equations Converting the Mass Flow to Other Units

The following simplified calculation equations can beused for applications with limited demand for precision such as in-house volume measurements and for adjustment purposes.

Conversion to Standard Volume Flow

The standard volume flow is primarily used in calculating gas volumes. The standard state of a gas isusually based on 273.15K (0 C) and 10135.5 Pa(1.01325 bar). The standard volume flow is calculated from the mass flow as follows:

Flowmetering of Liquids

Prerequisite conditions for simplification: Constant density, incompressible liquid, constant conduit interior diameter.

qq 1

NMN A table containing various standard densities is locatedin the Appendix.
,

dpdpqq

DBDmm

Conversion to Volume Flow

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